U.S. Pat. Nos. 6,030,718 and 6,468,682 relate to proton exchange membrane fuel cells, and more specifically, to fuel cell power systems which include a plurality of discrete fuel cell modules which are self-humidifying, and which offer a degree of reliability, ease of maintenance, and reduced capital costs that have not been possible, heretofore, with respect to previous fuel cells designs which have been primarily directed to stack-type arrangements. The teachings of these earlier patents are incorporated by reference herein.
With respect to fuel cells, in general, their operation are well known. A fuel cell generates electricity from a fuel source, such as hydrogen gas, and an oxidant such as oxygen or air. The chemical reaction does not result in a burning of the fuel to produce heat energy, therefore, the thermodynamic limits on the efficiency of such reactions are much greater than conventional power generation processes. In a proton exchange membrane fuel cell, the fuel gas, (typically hydrogen), is ionized in one electrode, and the hydrogen ion or proton diffuses across an ion conducting membrane to recombine with oxygen ions on the cathode side. The byproduct of the reaction is water and the production of an electrical current.
While the modular PEM fuel cells disclosed in the patents, referenced above, have operated with a great deal of success, there have been shortcomings which have detracted from their usefulness. Chief among the difficulties encountered in the commercial introduction of the fuel cells as seen in U.S. Pat. Nos. 6,030,718 and 6,468,682 is the multiplicity of parts required to fabricate and produce same. In particular, and as seen in U.S. Pat. No. 6,030,718, this particular patent shows an array of parts Which are utilized to transmit force substantially uniformly from the cathode covers of the respective PEM fuel cell modules to the underlying current collector which is pressed into ohmic electrical contact with the opposite anode and cathode sides of an ion exchange membrane. Again in U.S. Pat. No. 6,468,682, the fuel cell design as shown therein includes an array of rather sophisticated force application springs which lie in force transmitting relation relative to an underlying current collector which is forced by these same springs into ohmic electrical contact relative to the ion exchange membrane.
As should be understood from the teachings of these two patents, the costs attendant with the fabrication of these rather sophisticated parts, and the time required for assembly for these PEM fuel cell modules is significant. Moreover, manufacturing variations which may occur from time-to-time in these parts may result in decreased performance of the individual ion exchange membranes which are incorporated within these individual PEM fuel cell modules. In addition to the shortcomings noted above, difficulties have arisen from time-to-time regarding the operation of the PEM fuel cell modules in high temperature environments.
Accordingly, a proton exchange membrane fuel cell, and method of forming a fuel cell which achieves the benefits to be derived from the aforementioned technology, but which avoids the detriments individually associated with these novel PEM fuel cell modules, and stack-type fuel cells is the subject matter of the present invention.